Wed Jan 20 08:27:09 UTC 2010  pix@kepibu.org
  * Handle :case-sensitive properly
  
  If the first clause doesn't match due to mismatched case, it would
  roll down to the second clause, causing case-differing strings to
  erroneously match.  By checking for case again, we can avoid this.
  
  Note, however, that this does not fix the similar but unrelated
  inconsistent usage of *unify-string-case-sensitive-p* and
  *unify-string-case-insensitive-p* (the former being used in the code
  and the latter appearing in documentation).  That bug will remain
  until the canonical form is decided upon.
diff -rN -u old-cl-unification/unifier.lisp new-cl-unification/unifier.lisp
--- old-cl-unification/unifier.lisp	2014-07-15 03:13:54.000000000 +0000
+++ new-cl-unification/unifier.lisp	2014-07-15 03:13:54.000000000 +0000
@@ -96,7 +96,7 @@
 otherwise an error of type UNIFICATION-FAILURE is signaled."
   (cond ((and case-sensitive (char= a b))
          env)
-        ((char-equal a b)
+        ((and (not case-sensitive) (char-equal a b))
          env)
         (t
          (error 'unification-failure
@@ -118,7 +118,7 @@
 otherwise an error of type UNIFICATION-FAILURE is signaled."
   (cond ((and case-sensitive (string= a b))
          env)
-        ((string-equal a b)
+        ((and (not case-sensitive) (string-equal a b))
          env)
         (t
          (error 'unification-failure